A pneumatic tool such as an air hammer normally comprises three combined sections. The first section includes the tool s air inlet and usually also includes a handle for the manual manipulation of the tool. The tool's second section contains the air-powered motor. The third section of the tool comprises a retainer that removably secures a bit/work-contacting implement to a distal end of the tool.
To operate the tool, a user grasps the tool's handle and then actuates a trigger mechanism that causes a valve to allow pressurized air to flow to the tool's motor. In the case of a pneumatic hammer, the air-powered motor includes an elongated cylinder that houses a piston. The acceleration forces associated with the pressurized air that cause the reciprocating movement of the piston, also cause movement (vibration) of the cylinder and attached handle generally at a frequency of 20 to 40 cycles per second.
Furthermore, when the piston contacts the working implement, a large impact occurs which also creates a strong vibration which is transferred through the tool. The impact induced vibration commonly excites other components of the tool so that they vibrate at their natural frequencies which frequencies are generally higher than the fundamental operating frequency of the tool which may be termed impacts or blows per minute. Since the tool operates at a relatively high speed, the operator often finds the strong and seemingly continuous vibrations which are not only uncomfortable but tiring.
In the past, a large number of inventors have tried to create pneumatic tools in which the severity of the transmitted vibrations are reduced. The modified tools normally include some form of spring or air cushion that functions to absorb the created vibrations before they can be transmitted to the operator. To the extent that any of these versions are effective in reducing vibration, they generally do so at only the higher frequencies which are the vibrations created due to impact and thus do not isolate the vibrations at the tool components fundamental frequencies. Also, the prior art tools are usually quite complicated, expensive to produce and have a less than optimum durability.